Ruttler Mills PLLC

Seattle Patent Attorneys and Trademark Lawyers

Prosecution Laches

Posted Friday, October 5, 2012 by Mike Cicero

When defending itself against allegations of patent infringement, a defendant may do more than simply argue that its actions did not infringe upon the claims of the plaintiff’s patent. The defendant can raise one or more defenses to the allegations and, if the defendant can establish that one applies, the court may hold the patent unenforceable. Some possible defenses a defendant might raise include arguing that: the patent is invalid; the plaintiff committed patent exhaustion applies due to an authorized sale of the article, and/or prosecution laches renders the patent enforceable. This article introduces the defense of prosecution laches both generally and as applied to the recent case of Cancer Research Technology Ltd. v. Barr Laboratories, Inc., 625 F.3d 724 (Fed. Cir. 2010).

Generally, laches is a doctrine that bars a party from enforcing a right after an “unreasonable delay in pursuing [the right] in a way that prejudices the party against whom relief is sought.” Black’s Law Dictionary (9th ed. 2009). In looser terms, laches is also known as sleeping on one’s rights. Prosecution laches is simply the general doctrine as applied in defense to allegations of patent infringement, and if its is successfully invoked it may render the issued patent enforceable. To successfully invoke the doctrine a defendant must show that (1) the patent issued only after an “unreasonable and unexplained delay in prosecution,” and (2) prejudice based on the intervening rights of the defendant or the public during the period of delay. Cancer Research Technology Ltd., 625 F.3d at 729. The court further explained that to establish prejudice the defendant “must show evidence of intervening rights, i.e., that either the accused infringer or others invested in, worked on, or used the claimed technology during the period of delay.” Id.

A notable distinction between the general laches doctrine and the more specific prosecution laches is that the generalized doctrine requires a showing that the plaintiff delayed in enforcing a right against the defendant whereas prosecution laches may be established by a showing that the plaintiff delayed in obtaining its right in the first place, i.e. it delayed in the patent prosecution process at the end of which it actually obtained a right in the form of a patent. Id. at 729-30.

The patent contested in Cancer Research Technology Ltd., U.S. Pat. 5,260,291, certainly had a lengthy prosecution history as can be seen by its earliest priority date of August 24, 1981, and its grant date of November 9, 1993. Essentially, the 12 year prosecution of this patent was continually “[delayed] by eleven continuation applications, ten abandonments, and no substantive prosecution for nearly a decade.”* Id.* at 728. Originally, the district court found that the delay “was unreasonable and a sufficiently egregious misuse of the patent system to bar enforcement of the ′ 291 patent for prosecution laches.” Id. The U.S. Court of Appeals for the Federal Circuit, however, reversed.

The Court of Appeals did decide whether the delay was unreasonable and unexplained because, in its view, the case turned on the a lack of prejudice. It ruled that Barr failed to establish that it, or the public, was prejudiced by Cancer Research’s delay in prosecution.

The court was not persuaded by bars argument that any unreasonable and unexplained delay in prosecution inherently prejudices the public if that delay extends the patent term into the future because, according to the court, “the public has benefited here by the fact that Cancer Research did develop and market [the invention].” Id. at 732. Regarding Barr’s argument that it as a company suffered prejudice, the court took note that Barr did not file for an Abbreviated New Drug Application, which seeks approval to sell a generic form of an existing approved drug, until more than thirteen years after Cancer Research’s patent issued. The court further stated that Barr failed to introduce any evidence that anyone was deterred from entering the market based on Cancer Research’s delay in prosecution and, as such, there was no evidence of the intervening rights required to establish that the delay prejudiced anyone.

For these reasons, the Court of Appeals held that the prejudice element, which is required to invoke the prosecution laches defense and which the district court failed to address, was not successfully established by defendant Barr in this case.

In closing the court noted that cases like Cancer Research Technology Ltd. will probably occur infrequently, if at all, in the future because the term of patents filed on or after June 5, 1995, is measured from the effective filing date and not the issue date. Therefore, patent applicants are now incentivized to be expedient throughout the patent prosecution process because a delay in prosecution will actually shorten the term of the patent’s enforceability.